Anole Annals

A while back, Nancy Greig, Director of the Cockrell Butterfly Center at the Houston Museum of Natural Science, reported on an interaction with Freddie, her 27-pound dog, and a brown anole. Well, Freddie’s been at it again!

Here’s what Nancy has to say:

That dog-Anolis sagrei interaction I sent a photo of several months ago was not a one-off. Yesterday Freddie encountered another good-sized male that again would not back down. He could have run away, but seemed to think he was much bigger that he was.

I also “tested” him by touching his tail. He opened his mouth and extended his dewlap (I did this more than once), but did not try to run away. He could easily have run to hide, but like the first one, was extremely feisty (or had a death wish). I’m not sure if he eventually got away, but he certainly had many opportunities that he did not take.

I think it’s just the big male anoles that are so tough/stupid. The smaller ones run away.

Adult male Anolis onca from Isla de Margarita basking, by Gabriel N. Ugueto

We all know that anoles have subdigital lamellae; however, there is one species in which these lamellae are lacking: Anolis onca, which is known for being a sand-dwelling anole. In 2011, Dr. Jennifer Velásquez and colleagues published a paper in SABER, in which they studied the differences in thermal ecology and the activity pattern of male and female Anolis onca in Araya Peninsula, Venezuela, during the dry and wet season in a dry forest (10 m a.s.l). This study was conducted from September 2004 to April 2005, during which time 56 individuals were captured (15 females and 41 males). Dr. Velásquez and colleagues measured body temperature (T_b), substrate temperature (T_s) on the capture site, and air temperature (T_a).

Dr. Velásquez and colleagues found that in males and females, the T_b was higher during the dry season compared to the wet season: 33.6 ºC (30.0 – 37.2; n = 23) and 33.6 ºC (30.0 – 35.5; n = 7) for males and females, respectively, during the rainy season, and 34.4 ºC (33.0 – 35.8; n = 18) and 34.3 ºC (34.0 – 35.7; n = 8) during the dry season. Mean T_a and T_s were also higher during the dry season compared to the rainy season; during the dry season, T_a was 37.4 ± 0.69 ºC (n = 30) and T_s was 38.4 ± 0.69 ºC (n = 30), while during the rainy season, T_a was 33.9 ± 0.82 ºC (n = 26) and T_s was 34.9 ± 1.58 ºC (n = 26). In addition, Dr. Velásquez and colleagues found that A. onca changes its timing of activity depending on the season. During the rainy season, A. onca is more active from 9:00 am to 10:00 am, and during the dry season from 12:00 am to 1:00 pm; during both seasons, there is low activity from 3:00 pm to 5:00 pm.

The authors argued that there is a relationship between Tb, Ta and Ts during the rainy and the dry season, in which the thermophysiology of A. onca is influenced by the climate variability of the microhabitat it occupies, suggesting that this species is a thermoconformer. In conclusion, the body temperature of this species varies during the day and across seasons, and it also varies as air and substrate temperature vary.

Abstract:

Aspects of the thermal ecology and activity pattern of the lizard, Anolis onca, during the dry and rainy season, and both periods in a belt of xerophytic forest located in the Araya Peninsula, Sucre state, Venezuela. The mean body temperature of A. onca was 33.9 ± 1.50 ºC in both periods to A. onca, while it reached 34.4 ± 0.75 ºC during the drought period and 33.6 ± 1.87 °C during the rainy period. In both climate periods, we found positive and significant correlations between body temperature with air and substrate temperature. The results suggest that thermoregulation is done passively, influenced by microhabitat temperature (air and substrate). There was a unimodal daily activity pattern during both periods. The thermal niche breadth was greater in males, while niche overlap between sexes was higher during the rainy period.

Read the full paper here!

Hello all,

Ben Marshall and my colleagues at the Reptile Database have recently tried to take stock of the reptile photos on some of the most prominent web sites

Anolis porcatus, female, near Matanzas, Cuba – a close relative of the most photographed Anolis ever, A. carolinensis.

that collect nature photos, namely, iNaturalist, Flickr, CalPhotos, HerpMapper, Wikimedia, and the Reptile Database itself. We came up with more than 1 million reptile photos, the vast majority being on iNat. While the Reptile Database has much fewer photos overall, we do have photos of close to 6000 reptile species (with iNat having about 6500 species). While about 8000 reptile species have photos on these sites, almost 2000 have photos in only one of them (see Marshall et al. 2020 for details).

That begs the question “how do anoles fit into that picture?” — literally. Of the 436 species of anoles that the Reptile Database currently lists, at least 367 have photos on some of these websites, again with iNat leading (302 species), and all the others trailing far behind with Flickr (177), the  Reptile Database (173), Calphotos (101), Herpmapper (92), and Wikimedia (55). Not surprisingly, both Anolis carolinensis and A. sagrei are among the top-10 most photographed reptiles with about 30,000 photos each on iNaturalist alone! By contrast, there are at least 67 species of anole of which there seem to be no photos on any of these sites (and possibly nowhere else on the internet). Here is the list: Anolis_Photos (Excel spreadsheet).

As pointed out in our paper, photos are not just nice to look at, they do carry a substantial amount of information, as all anologists doubtlessly know: besides morphology, you can see behavior, diet, ecological adaptations, habitats, and many other things on a photo (or video).

That said, at the Reptile Database, we are increasingly moving towards standardized photos of reptile species, ideally showing diagnostic characters. To see what I am talking about, take a look at Levi Gray’s excellent dewlap panels that he has presented here at Anole Annals and in his blog. Similarly, over the past year or two, I have taken pictures of more than 1000 reptile specimens in various collections (mostly NOT of anoles, admittedly), mainly to document such characters. They will go into the Reptile Database over the coming year (or probably years). Below are two examples, Anolis reconditus from Jamaica, and A. carolinensis from the Bahamas.

Anolis reconditus, CMNAR 9931, from Jamaica. Note the keeled scales which are not visible on any of the photos on iNaturalist.

Anolis carolinensis, ZMB 18723, Nassau, Bahamas. Compare to A. reconditus.

Obviously, it would be better if we had photos like these of all anoles — or all reptiles for that matter. Well, we have to start somewhere. In addition to the >18,000 photos in the Reptile Database, we need many more to document morphological diversity. Again, one idea is to use these photos to extract information such as character data. So, if you happen to have photos of any of those undocumented (or under-documented) species, please consider sending them to photos@reptile-database.org — or to one of the other sites, of course. Thanks!

Anolis marmoratus, by Kristin Winchell. This photo is featured in the Anole Annals 2021 calendar!

Last year, Rafael Alejandro Lara Resendiz (Centro de Investigaciones Biológicas del Noroeste and Instituto de Diversidad y Ecología Animal) published a paper in Acta Biológica Colombiana, in which he summarizes nocturnal activities in exclusively diurnal reptiles and addresses the question of how this behavior affects their ecophysiology.

Ectotherms – reptiles, amphibians, fish, and most invertebrates – need environmental temperature to produce heat internally, meaning that these organisms depend upon an external source of heat to regulate their internal functions. Thermoregulation is a complex physiological process that is involved in every activity that allows ectotherms to survive in nature (e.g., feeding and reproductive behavior, growth patterns, locomotion, digestion). In this regard, ectotherm species differ in their thermoregulation behaviors; some species are more active during the day while others are active during the twilight. However, some species that are known to be diurnal have been found active during the twilight. Lara-Resendiz (2020) address four-point in his work. Specifically, he 1) reviews nocturnal activity events in reptiles considered exclusively diurnal; 2) discusses the ecophysiological implications on this topic; 3) identifies the aspects that have not yet been approached in-depth; and 4) proposes possible directions for future lines of research.

Several species that are known to be exclusively diurnal have been observed carrying out nighttime activities, including lizards (e.g., Agama, Anolis, Callisaurus, Dipsosaurus, Gerrhonotus, Liolaemus, Ophisaurus, Phrynosoma), snakes (e.g., Charina, Contia, Masticophis), tortoises (e.g., Gopherus, Geochelone), marine turtles (e.g., Chelonia). Particularly, reptiles inhabit a wide variety of habitats including tropical and cold areas, desserts, high and low elevation areas, and the sea. Living in this different environment may cause lizards to have different patterns of activities throughout the daytime or nighttime: geographical location and thermal environmental variability have a tight relationship with the period of activities of all ectotherms.

One hypothesis has been proposed to explain the nocturnal behavior in diurnal species, in which ectotherm species have different optimal temperatures in the photophase (daytime) and scotophase (nighttime). In this regard, by selecting different environmental temperatures during each phase species that are active during the day can also be active during the night. In some other cases, species that are known to be strictly diurnal can behave opportunistically during the night due to ecological or physiological conditions – high levels of humidity and/or low predation rate, and prey can be easily spotted. Another possible explanation of this change in the time of activity in lizards and snakes is the heterogeneity or homogeneity in the temperature variation in the environment, where species that inhabit stable habitats cannot increase the length of their foraging time, while those species in more heterogenous habitats have more opportunities to extend their activity period due to their wide-body temperature range; this hypothesis has not been tested yet.

Currently, ectotherm species are facing the consequences of the change in the global temperature because they depend on the temperature of their habitat. Climate change is causing species to overheat, therefore, changing their diurnal activity and increasing vulnerability in their population structure. Particularly, these effects have been stronger in the atropical ectotherms which are inhabiting places where the temperature is near their optimal temperature. This suggests that the nocturnal opportunistic behavior of some ectotherm species could be a response to the increasing temperatures.

In conclusion, we need to address questions regarding why these changes in the foraging activity of ectotherm is occurring, and how their ecology and physiology is or could be affected by foraging during the nighttime.

Abstract:

This review is the first to summarize published studies that document nocturnal activity events in reptiles previously considered exclusively diurnal. The ecophysiological implications of this nocturnal activity in tropical and high-latitude environments are described and discussed from the perspective of optimal activity temperature ranges, tolerance thresholds, activity periods, cathemerality, voluntary hypothermia, and its importance in the face of global climate change. Gaps in the research field are finally identified, and new lines of study are proposed.

Read the full paper here!

Six-toed brown anole reported by DeVos et al. 2020 in Herp. Review

Read all about them in the most recent (December 2020) Natural History Notes section of Herpetological Review (searching on “Anolis” will get you to these reports expeditiously in the pdf).

From Mendyk et al., Herp. Review, 2020